Adults: The adult Opius dissitus are black in color. The antennae are black and thin, and almost the same length as their body.

Eggs:Opius dissitus females lay their eggs directly inside the late stage Liriomyza larvae bodies. The average size of the egg is about 0.28 mm (Bordat et al. 1995a).

Larvae: The Opius dissitus larvae develop inside the Liriomyza leafminer larvae. However, the parasitized leafminer larvae still consume the tissue of plant leaves until their pupation. The Opius dissitus larvae develop through two instars inside the leafminer larvae (Bordat et al. 1995a), and eventually kill the leafminer in the pupal stage. The mature Opius dissitus larvae then pupate inside the leafminer pupae. The optimal temperature for Opius dissitus development on host of Liriomyza trifolii is reported as 25–30°C (Bordat at al. 1995b).

Pupae:Opius dissitus early stage pupae are yellow and have red eyes, while the mature stage pupae are black in color. Opius dissitus adults emerge out of the leafminer pupae. One adult emerges from a single parasitized pupa (unpublished data, Li et al.)

Figure 2. Early stage pupa of Opius dissitus Muesebeck, an endoparasite of Liriomyza leafminers. Photograph by Jian Li, University of Florida.

Figure 3. An adult Opius dissitus Muesebeck, an endoparasite of Liriomyza leafminers, emerging from the leafminer's pupa. Photograph by Jian Li, University of Florida.

In Florida, Opius dissitus larvae were found and collected, then reared to adults, from the leaves of several crops infested by Liriomyza leafminers (Stegmaier 1972, Schuster and Wharton 1993). Important Liriomyza economic pest species include the pea leafminer, Liriomyza huidobrensis (Blanchard); the vegetable leafminer, Liriomyza sativae Blanchard; and the American serpentine leafminer, Liriomyza trifolii (Burgess).

Opius dissitus is a potential biological control agent for Liriomyza leafminers on vegetable and ornamental plants. Opius dissitus was found to be the most abundant parasitoid (63% of all the parasitoids) of Liriomyza trifolii on snap bean crops in south Florida, and the seasonal density of Opius dissitus had a similar pattern with Liriomyza trifolii (unpublished data, Li et al.). Opius dissitus was also found to be one of the major hymenopteran parasitoids of Liriomyza leafminer on tomato crops (Schuster and Wharton 1993). Petitt (2004) reported that Opius dissitus was reared and released to control Liriomyza leafminers at the Walt Disney World Resort.